detect_mshta_inline_hta_execution.yml

name: Detect mshta inline hta execution
id: a0873b32-5b68-11eb-ae93-0242ac130002
version: 6
date: '2021-09-16'
author: Bhavin Patel, Michael Haag, Splunk
status: production
type: TTP
description: The following analytic identifies "mshta.exe" execution with inline protocol
  handlers. "JavaScript", "VBScript", and "About" are the only supported options when
  invoking HTA content directly on the command-line. The search will return the first
  time and last time these command-line arguments were used for these executions,
  as well as the target system, the user, process "mshta.exe" and its parent process.
data_source:
- Sysmon Event ID 1
search:
  selection1:
    OriginalFileName: MSHTA.EXE
  selection2:
    Image|endswith: mshta.exe
  selection3:
    CommandLine:
    - '*vbscript*'
    - '*javascript*'
    - '*about*'
  condition: (selection1 or selection2) and selection3
how_to_implement: To successfully implement this search you need to be ingesting information
  on process that include the name of the process responsible for the changes from
  your endpoints into the `Endpoint` datamodel in the `Processes` node. In addition,
  confirm the latest CIM App 4.20 or higher is installed and the latest TA for the
  endpoint product.
known_false_positives: Although unlikely, some legitimate applications may exhibit
  this behavior, triggering a false positive.
references:
- https://github.com/redcanaryco/AtomicTestHarnesses
- https://redcanary.com/blog/introducing-atomictestharnesses/
- https://docs.microsoft.com/en-us/windows/win32/search/-search-3x-wds-extidx-prot-implementing
tags:
  analytic_story:
  - Suspicious MSHTA Activity
  - Living Off The Land
  asset_type: Endpoint
  confidence: 100
  impact: 90
  message: An instance of $parent_process_name$ spawning $process_name$ was identified
    on endpoint $dest$ by user $user$ executing with inline HTA, indicative of defense
    evasion.
  mitre_attack_id:
  - T1218
  - T1218.005
  observable:
  - name: user
    type: User
    role:
    - Victim
  - name: dest
    type: Hostname
    role:
    - Victim
  - name: parent_process_name
    type: Process
    role:
    - Parent Process
  - name: process_name
    type: Process
    role:
    - Child Process
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  risk_score: 90
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1218.005/atomic_red_team/windows-sysmon.log
    source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
    sourcetype: xmlwineventlog